Shale retorting method and apparatus



Nov. 8, 1955 K. M. ELLIOTT SHALE RETORTING METHOD AND APPARATUS FiledSept. 13, 1951 fry/W 5y/#Lf H 7' TOR/VE Y 2,723,225 Epatented Nov. 8,1955 United States Patent @Ence SHALE RETORTING METHOD ANTI) APPARATUSKenneth M. Elliott, Woodbury, N. J., assigner to Socony MobilOilCompanyJnei, a@ corporation, of N ew York Application September 13,1951, Serial No. 246,462`

9 Claims. (Cl. 202-6) This invention relates to'- ay method andapparatus for obtaining valuable hydrocarbons from` shale and; the like.More particularly, the present invention is-.concerned with an improvedprocess and apparatus: in which shale is retorted in an eiicient mannerrutilizingthe coldk shale feedl as a medium for effecting condensation'of oil vapors emitted upon roasting the shale.

It is common practice in the art to. recover oils from solid oil-bearingor oil-producing materials ands particularly to recover shale oil fromoil shale. As is well recognized, ordinary oil shale does not containoil assuch but a solid bitumen type material known asl kerogen which,when heated, breaks down into gases, petroleum-like liquids, and carbon.

The recovery of oil from oily shalehasheretofore been accomplished byheating the shale at; elevated-- temperatures suiiicient to educt theoil and separate it from residual mineral matter. However, commercial:shale retorting operations previously employed have been generallycumbersome and` expensive, involving large equipment and operating costsper unit ofL shalev throughput.

vimportant factors contributing to these economic burdens have been poorheat recovery in thelretort systems, and

the expense, equipment, and timei'consumedin subsequently recovering theproducts of retortation.

A major object of this invention, accordingly, is the provision of amethod and apparatus inwhichV oil shale and the like may be eflicientlyretorted without the excessive heat loss which has been. generallyprevalent in the processes and equipment heretofore used. A furtherobject is to provide amethod and apparatusfor retorting oil shalewherein intimate contact betweenvaporous shale oil products andcondensed liquidl shale oil is obtained. A still further object is theprovision of a compact; apparatus for retorting oil shale affordingconvenient means for subsequent recovery of. the liquid shaleoil. Theseand other objects which will be apparent to those skilled in the art areaccomplishedl in accordance with the present invention. f

`Operation of the process and apparatus` described herein comprises thecontinuous passage of crushed shale downwardly as a solidmovingbed'through an elongated vertical vessel having a condensing zonewherein gaseous products rising from a lower retorting zone ofsaidvessel undergo condensation While flowing countercurrently to said solidmoving bed, said crushed shale and gaseous products passing through'azone of said vessel intermediate said condensing and said retortingzones in which a gas seal is maintained by the introduction of a= streamof an inert gas in an. amount suicient to prevent the downward iiow ofcondensed liquid shale oil therethrough without substantiallyinhibitingl thev downward passage of crushed shale.

It has been found, in accordance with the present invention, that theprovision ofk a gas seal by introduction of a high velocity stream ofinert gas between the retorting and condensing zones of a shale retortwherein shale oil is condensedk on cold` shaley feed provides aneffective means for supporting andV maintainingfthe liquid' shale oilsoobtained in the condensingzone of the retorting vessel and thuspreventing its downward flow by gravity intocthe retorting zone of saidvessel; The gaseous stream conducted to the gas seal zone may be any gasinert under the operating conditions of the retort. Typical examples ofsuitable gases are flue gas, steam, and nitrogen. The gas seal zone mayalso be maintained by the introduction at, a point intermediate thecondensing and retorting zones of a liquid capableofI ashing to an inertvapor under the temperature-conditions maintained inthe retort.A-particularly feasible liquid for such purpose is water. In a preferredembodiment,` of` the invention, the-gas seal Zone is provided byrecycling a stream of ,retorty gas withdrawn from the, upper portionofthe retorting vessel and introduced at a point intermediate theretorting and condensing zones thereof.V lt will; be under,- stood thatthe amount and velocity of gas introduced into-the gas seal zone of theshale retorting vessel employed herein is such as to prevent condensedshale oil from passing into the retorting zone of the vessel butinsufficient to prevent the downward passage of crushed shaletherethrough.

The invention may be further understood by reference to the attacheddrawing, which represents a schematic arrangement of apparatus forcarrying out the process of the invention. Referring more particularlyto the drawing, cold, crushed, raw oil shale is introduced into hopper10. The shale moves by gravity from hopper 1) through feed leg 11provided with a Asuitable flow control means not shown and passes intothe upper portion of retorting vessely 12. A. gas, such. as flue gas orsteam,` is desirably introduced into feed leg 111 through conduit 13 toforestall the upward ow of gaseous. retort products therethrough. As theshale descends; through the retorting vessel, it passes rst through acondensing zone where liquid shale oil condensed from gases. generatedduring retorting is collected in .av relatively static pool. The liquidproduct, together withV noncondensable gases, is withdrawn from thispool through outlet pipe 14. leading to a liquid-gas separator 15.Liquid shale oil collects in, the bottom of separator 15 and iswithdrawn therefrom through draw-off pipeA 16. Non-condensable gases areremoved from separator 15 through pipe17. A b afe 1S is affixed to theinterior wall of retorting.l vesself12, overlying the outlet connectionlof pipe 14, to prevent entrainment of granular, solid shale particlesin the product oil. y

The descending shale, now wet with shale oil, passes from the condensingzone of retorting vessel 12, through a gas seal zone into which a highvelocity gas stream, is conducted through conduit 19. The amount andvelocity of gas passing upwardly through the gas seal Zone is such as toprevent the downward flow of condensed liquid shale. oil but insuicientto prevent the downward passage of crushed shale. As set forthhereinabove, the stream conducted to the gas seal Zone through conduit19.may. be, any inert gas or liquid capable of flashing to inert vaporunder the temperature conditions maintained in the retort. In apreferred lembodiment of the; invention, a stream of retorting gas iswithdrawn froml the upper portion of the gas seal Zone through outlet`pipe. 20. A baffle plate 21 aiixed to the interior wall of the retortoverlying the outlet connection` of pipe 2G. prevents withdrawal ofgranular solid shale particles at this point. After separating anyliquid shale oil from' said stream in liquidgas separator 22, the gas.is passed through conduit 23 to blower 24 and then recycled underpressure to the retorting vessel through pipe 19. Shale oil whichcollects in separator 22 is removed from the bottom thereof throughoutlet pipe 25. Instead of employing recycle gas, water may beIintroduced throughv conduit 1.9 by means ofA pipe.

26 and sprayed into the retorting vessel, the resulting steam providingthe high velocity gas required in the gas seal zone. It is also withinthe purview of this invention to jointly employ a stream of recycle gasand water to provide the high velocity gas stream required in the gasseal zone. Likewise, other fluids or mixtures thereof which are inertunder the operating conditions of the retort may be employed inproviding the desired gas seal.

The downwardly moving shale is further heated in the gas seal zone bycountercurrent heat exchange with the hot vapors rising from theretorting zone immediately below. As the rising hot vapors give up theirheat to the descending shale passing through the gas seal zone, thecondensable portion of the vapors is liquicd. It is for the purpose ofminimizing the natural downward flow of this condensate and ofpreventing the pool of liquid in the overlying condensing zone fromflowing down into the retorting zone that the above-mentioned gas sealzone is maintained at a point intermediate the condensing zone andretorting zone.

Upon emerging from the gas seal zone, the preheated shale continues itsdownward passage through a retorting zone and a burning zone wherein itis contacted with an oxygen-containing gas, such as air, introducedthrough conduit 27. Upon contact of the oxygen-containing gas with hotshale, residual combustible matter is burned from the shale, therebyproviding the heat required for retorting. The combustion products flowupward in admixture with the vapors resulting from decomposition of thekerogen content of the shale and said combustion products ultimatelyleave the top of retorting vessel 12 along with noncondensable retortgas and liquid shale oil through outlet pipe 14.

The hot shale flows downwardly from the burning zone and is furthercooled by the introduction of a cooling medium such as water, steam, orthe like, suitably introduced through conduit 28 provided with controlValve 29.

For initially heating the shale, hot flue gas is introduced throughconduit 30, Valve 29 being closed and valve 31 being open. Afteroperation of the retort is begun, valve 31 is closed and valve 29 isopened as the introduction of cooling medium is desired. Spent shaleflows out the bottom of retorting vessel 12 through outlet pipe 32, the

rate of llow being conveniently controlled by valve 33. The introductionof a cooling medium is not considered essential to successful operationof the instant retort but is advantageous in that it assists in upwardtransfer of heat to the retorting zone and further provides a seal bysome downward leakage on outlet pipe 32, thereby serving to facilitatethe desired upward movement of gaseous retort products.

It is essential in accordance with the present method of operation thata gas seal zone be maintained intermediate the retorting zone andcondensing zone and that the velocity and amount of gas introduced intothe gas seal zone be such as to prevent the downward flow of liquidshale oil through the retorting vessel while permitting crushed shale topass downwardly through the retorting vessel. The gas seal zone furtherserves the purpose of affording a heat transfer zone where the productgases are cooled and cold descending shale is preheated.

The amount of gas introduced to the gas seal zone should, in addition,be correlated with the cross-sectional area of the retorting vesselemployed. The vessel utilized in the present process has a cross-sectionsubstantially uniform throughout the condensing, gas seal and retortingzones thereof. As will be realized, the larger the crosssectional areaof the retorting vessel employed, the greater is the quantity of gasrequired to maintain the desired seal. In general, it is preferred tointroduce the high velocity gas stream to the gas seal zone in a uniformmanner through a plurality of nozzles spaced at predetermined intervalsextending horizontally across a section of the retorting vessel.

Various other modifications and refinements of; the.' i013?- goingprocess may be made, depending largely upon the nature of the shale oilproduct desired. Thus, in some instances, it may be desirable to controlthe heat release during combustion by adjustment of the incoming streamof air or other oxygen-containing gas to cause the condensing zone tooperate at a temperature suiciently above the pour point of the productoil to prevent deposition of wax or other solid hydrocarbons in saidcondensing zone. Also, it may be advantageous in some instances, wherethe presence of water in the retort is considered detrimental, topreheat the raw shale being introduced into hopper 10 to a temperatureabove the dew point of the retort gas to obviate possible condensationof water in the condensing zone.

In practice of this invention, the shale is suitably crushed. Thepreferred size should pass a 2-inch mesh sieve and be retained on a1t-inch mesh sieve. However, crushed shale outside of this preferredmesh size may also be used. The temperature in the retorting zone isgenerally between about 800 F. and about l500 F. depending upon the typeof shale employed and the nature of the products desired.

It is to be understood that the crushed shale flows downward through theapparatus of this invention as a compact moving bed and that the unit isso designed that vapor velocities do not reach a Value sufliciently highto cause the descending solidsto boil to any appreciable extent. The useof a gaseous stream of high velocity in only a restricted portion of theequipment, namely, in the gas seal zone, affords Several advantages.Thus, adequate time for combustion and retorting can thereby be providedwithout making the apparatus unduly large, particularly in height.Moreover, erosion of equipment and shale is minimized by substantialelimination of high vapor velocities other than in the aforementionedgas seal zone.

Collection of the liquid shale oil in a pool inside the retorting vesselis also advantageous in that a high degree of contact between the risingvapors and the liquid oil is achieved, resulting in greater heatrecovery and improved adsorption of light hydrocarbons from the retortgas.

While the method and apparatus described herein have been particularlydirected to the recovery of shale Oil from oil shale, the presentinvention may be adapted for the recovery of oils from any solidsubstance. ingly, it is to be understood that the above description ismerely illustrative of preferred embodiments of the invention, of whichmanyvariations may be made within the scope of the following claims bythose skilled in the art without departing from the spirit thereof.

I claim:

1. A process for the recovery of shale oil from oil shale, whichcomprises feeding crushed raw oil shale to an elongated vertical retort,passing said shale downwardly through said retort while bringing thesame to ignition temperature, contacting the resulting hot shale with astream of oxygen-containing gas to. effect combustion of combustiblematter present therein, flowing hot vaporous products emitted from theheated shale upwardly through a zone wherein a gas seal is maintained inthe retort by the introduction thereto of a high velocity gas stream,passing said vaporous products upwardly from said zone and immediatelycondensing a portion thereof to liquid shale oil by contacting withcold, crushed, raw shale feed, maintaining a static pool of the liquidshale oil so obtained, passing said cold, crushed, raw shale, wet withoil, through the aforementioned gas seal zone, the introduction of saidgas stream to said zone being suflicient to prevent the downward ow ofsaid pool of liquid shale oil through said zone but insulcient toinhibit the downward passage of crushed oil shale therethrough, removinga stream of non-condensable gases liquid shale oil from the upperportion of said retort and. withdrawing a stream portion of'fsaid-`retort;

2.; kIn a method for producingqshal'e oil"I from voil shale byheating adownwardly moviugrbed of crushed oil shale and flowing the vaporousproducts so produced upwardly through said downwardlyl moving bed'su'chthat vaporous products rising from a lower retorting zone undergocondensation upon coming into contact with cold, crushed shale in anoverlying condensing zone, the improvement which comprises theintroduction of a gas stream at a point intermediate said retorting zoneand said condensing zone of velocity suiiicient to prevent condensedshale oil from passing into said retorting zone but insullicient toprevent the downward passage of crushed oil shale therethrough.

3. In a method for producing shale oil from oil shale by heating adownwardly moving bed of crushed oil shale and owing the vaporousproducts so produced upwardly through said downwardly moving bed suchthat vaporous products rising from a lower retorting zone undergocondensation upon coming into contact with cold, crushed shale in anoverlying condensing zone, the improvement which comprises recycling astream of retort gas to a point intermediate said retorting zone andsaid condensing zone of velocity suicient to prevent condensed shale oilfrom passing into said retorting zone but insuicient to prevent thedownward passage of crushed shale oil therethrough. n

4. In a method for producing shale oil from oil shale by heating adownwardly moving bed of crushed oil shale and owing the vaporousproducts so produced upwardly through said downwardly moving bed suchthat vaporous products rising from a lower retorting zone undergocondensation upon coming into contact with cold, crushed shale in anoverlying condensing zone, the improvement which comprises sprayingwater at a point intermediate said retorting zone and said condensingzone to provide lan amount of steam sucient to prevent condensed shaleoil from passing into said retorting zone but insuicient to prevent thedownward passage of crushed oil shale therethrough.

5. A process for the recovery of shale oil from oil shale, whichcomprises feeding crushed, raw oil shale to an elongated verticalretort, passing said shale downwardly through said retort while bringingthe same to ignition temperature, contacting the resulting hot shalewith a stream of oxygen-containing gas to effect. combustion ofcombustible matter present therein, flowing hot vaporous productsemitted from the heated shale upwardly through a zone wherein a gas sealis maintained in the retort by the introduction thereto of a water sprayaffording a high velocity stream of steam, passing said vaporousproducts upwardly from said zone and immediately condensing a portionthereof to liquid shale oil by contacting with cold, crushed, raw shalefeed, maintaining a static pool of the liquid shale oil so obtained,passing said cold, crushed, raw shale, wet with oil, through theaforementioned gas seal zone, the introduction of water to said zonebeing sutlicient to afford an amount of steam adequate to prevent thedownward flow of said pool of liquid shale oil through said zone butinsufiicient to inhibit the downward passage of crushed oil shaletherethrough, removing a stream of non-condensable gases and shale oilfrom the upper portion of said retort and withdrawing a stream of spentshale from the lower portion of said retort.

6.A process for the recovery of shale oil from oil shale, whichcomprises co-mingling crushed oil shale with hot ue gas to heat saidshale to ignition temperature, contacting the hot shale with a stream ofan oxygen-containing gas to etect combustion of combustible matterpresent in the shale, flowing hot vaporous products rising from theheated shale, together with gases formed during combustion, through agas seal zone maintained by the introduction thereto of a high velocitystream of gas of'lspent shalefrom the lower produced as hereinafterdescribed, condensing a portion of said vaporous productsv uponemergence from said zoieto-liquid shale-oil bycontactinget'hesame withcold, ci''shed, raw shale, maintaining a p'ooly of liquid. shale oilz'so obtainedy immediately overlying said gas seal zone, sidf pool beingsupported bythe high gas velocity Allow through said zone, passing saidcold, crushed, raw shale downwardly through said pool and then passingthe shale, wet with oil, through said zone countercurrent to the ow ofhot vaporous products therethrough, whereby the shale becomes heatedduring its passage through said zone and the hot counter-flowingvaporous products are cooled by heat exchange, withdrawing a stream ofretort gas and recycling the same under pressure to the aforementionedgas seal zone, withdrawing heated shale from said zone, bringing thesame into contact with the aforementioned stream of oxygen-containinggas to produce a further quantity of said vaporous products and residualspent shale, removing a stream of shale oil from said pool andwithdrawing a stream of said spent shale.

7. In a retorting apparatus for producing shale oil from oil shale, thecombination of an elongated vertical retorting vessel having a lowerretorting zone and an overlying condensing zone, means for introducingo-il shale into said retorting vessel, means for introducing hot iluegas into said retorting vessel, means for introducing anoxygen-containing gas into said retorting vessel, means for withdrawingand recycling a stream of retort gas from the upper portion of saidvessel to a point intermediate the retorting zone and the condensingzone of said vessel, an outlet pipe for withdrawing a stream of liquidshale oil from said condensing zone, means for cooling shale aftercombustion thereof, and means for removing cooled spent shale from saidretorting vessel.

8. In a retorting apparatus for producing shale oil from oil shale, thecombination of a retorting vessel provided with a lower retorting and anoverlying condensing zone, a conduit for introducing oil shale into saidretorting vessel, an inlet pipe for the introduction of a hot flue gasinto said retorting vessel, an inlet pipe for the introduction ofoxygen-containing gas into said retorting vessel, means for sprayingwater into said retorting vessel at a point intermediate said condensingzone and said retorting zone, an outlet pipe for the withdrawal ofliquid shale oil from said condensing zone and an outlet conduit forremoving spent shale from said retorting vessel.

9. In a retorting apparatus for producing shale oil from oil shale, thecombination of a retorting vessel having a lower retorting zone and anupper condensing zone, a conduit for introducing crushed oil shale intosaid retorting vessel, an inlet pipe for the introduction of hot fluegas into said retorting vessel, an inlet pipe for the introduction ofoxygen-containing gas into said retorting vessel, an outlet pipe forwithdrawing a stream of retort gas from the upper portion of saidretorting vessel, a liquid-gas separator for removing liquid shale oilfrom said stream, a blower for recycling said stream substantially freedof liquid shale oil to said retorting vessel at a point intermediate theretorting zone and the condensing zone thereof, an outlet pipe for thewithdrawal of liquid shale oil from said retorting vessel and an outletconduit for removing spent shale from said retorting vessel.

References Cited in the tile of this patent UNITED STATES PATENTS1,130,001 Maclurin Mar. 2, 1915 1,509,667 Catlim Sept. 23, 19241,631,637 Loughrey June 7, 1927 (Other references on following page) iUNITED STATES PATENTS Wallace Aug. 16, 1927 Herrick Dec. 29, 1931 SnyderMay 17, 1932 Karrick Mar. 14, 1933 5 8 Warner Jan. 7, 1936 Karrick July4, 1939 Kaufmann June 13, 1944 Barr et a1. Jan. 20, 1953 Kassel May 5,1953

2. IN A METHOD FOR PRODUCING SHALE OIL FROM OIL SHALE BY HEATINGDOWNWARDLY MOVING BED OF CRUSHED OIL SHALE AND FLOWING THE VAPOROUSPRODUCT SO PRODUCED UPWARDLY THROUGH SAID DOWNWARDLY MOVING BED SUCHTHAT VAPOROUS PRODUCTS RISING FROM A LOWER RETORTING ZONE UNDERGOCONDENSATION UPON COMING INTO CONTACT WITH COLD, CRUSHED SHALE IN ANOVERLYING CONDENSING ZONE, THE IM-PROVMENT WHICH COMPRISES THEINTRODUCTION OF A GAS STREAM AT A POINT INTERMEDIATE SAID RETORING ZONEAND SAID CCONDENSING ZONE OF VELOCITY SUFFICIENT TO PREVENT CONDENSEDSHALE OIL FROM PASSING INTO SAID RETORTING ZONE BUT INSUFFICIENT TOPREVENT THE DOWNWARD PASSAGE OF CRUSHED OIL SHALE THERETHROUGH.